Throw invalid operation if result set is null.

Signed-off-by: Josh Rees <[email protected]>

Author: joshdrees

src/MySqlConnector/MySql.Data.MySqlClient/MySqlDataReader.cs

@@ -362,7 +362,7 @@ internal DataTable BuildSchemaTable()
 		{
 			var colDefinitions = GetResultSet().ColumnDefinitions;
 			if (colDefinitions is null)
-				return null;
+				throw new InvalidOperationException("There is no current result set.");
 			DataTable schemaTable = new DataTable("SchemaTable");
 			schemaTable.Locale = CultureInfo.InvariantCulture;
 			schemaTable.MinimumCapacity = colDefinitions.Length;

tests/Conformance.Tests/DataReaderTests.cs

@@ -12,8 +12,5 @@ public DataReaderTests(SelectValueFixture fixture)
 
 		[Fact(Skip = "Deliberately throws InvalidCastException")]
 		public override void GetTextReader_returns_empty_for_null_String() { }
-
-		[Fact(Skip = "https://github.com/mysql-net/MySqlConnector/issues/678")]
-		public override void GetSchemaTable_throws_after_Delete() { }
 	}
 }

tests/SideBySide/DataTypes.cs

@@ -1227,7 +1227,11 @@ public void GetSchemaTableAfterNextResult()
 					}
 
 					Assert.False(reader.NextResult());
+#if BASELINE
 					Assert.Null(reader.GetSchemaTable());
+#else
+					Assert.Throws<InvalidOperationException>(() => reader.GetSchemaTable());
+#endif
 				}
 			}
 		}